Medical devices such as intramedullary (IM) rods may include a biocompatible coating (film) applied thereto for controlled release of an included medicament, such as antibiotics (e.g. vancomycin) and anabolic agents (e.g. statin). Biocompatible coatings may further include a polymer matrix for the medicament that will bioresorb over time, such as chitosan or collagen.
Simple solvent casting of the medicament/polymer matrix composite may be utilized to provide a biocompatible coating, but such may be impractical based on the topologically complex surfaces of many medical devices (e.g. curved, grooved rods and plates with through holes for screws, etc.).
Alternatively, electrophoretic deposition (EPD) from aqueous systems may be used to deposit the matrix on a topologically complex surface of the device, however, such may suffer from the production of hydrogen gas bubbles at the anode, i.e. the metallic substrate of the medical device (e.g. titanium (Ti), magnesium (Mg), or stainless steel (SS)) which may disrupt coating integrity.
However, in many situations the medicament and/or supporting polymer matrix are not water, but rather organo-soluble. In such situation, an organic solvent may be used in the electrophoretic deposition which will include aprotic organic solvents (e.g. tetrahydrofuran, methyltetrahydrofuran, methylene chloride). For example, bioresorbing polymers such as poly(d,l lactide-glycolide) (PLGA), poly(1-lactide) (PLLA) and polycaprolactone (PCL) are not water soluble at any pH, unlike other resorbing polymers, such as chitosan, which is water soluble at a pH of less than 6.
Certain inorganic nanoparticles themselves may act as medicaments for specific biomedical purposes. For example, strontium ion (Sr+2) exhibits anabolic/anticatabolic action useful for bone defect and fracture repair. Nanoparticles containing strontium (Sr) have been formed directly on an anodized titanium (Ti) surface (titanium dioxide (TiO2)) by hydrothermally treating after exposure to strontium ion (Sr+2) solutions to form SrTiO3.